A B22 lamp holder is the socket that accepts a bayonet cap bulb with a base 22 millimetres in diameter, the standard light-bulb fitting in Britain and many Commonwealth countries. The bulb is pushed in and twisted so that two small pins on its side lock into slots in the holder.
The bayonet fitting was adopted in Britain in the early years of domestic electric lighting, and it remains the most common household fitting, alongside the Edison screw used across much of Europe and North America. Early B22 holders were made of brass, often with a switch built into the body, and porcelain or Bakelite holders followed later. When antique lamps, lanterns and chandeliers are converted or rewired for use in Britain, B22 holders are frequently fitted, sometimes in brass to match the original metalwork. Old holders should be inspected carefully, as worn insulation, loose contacts and the lack of an earth connection can be dangerous. Any rewiring should be carried out by a qualified electrician, and many dealers have lights safety tested before sale to give buyers confidence.
